With the fast development of display technologies, liquid crystal displays (LCDs), as flat plate displays, are more and more used in the high-performance display field because of their features such as small volume, low power consumption, free of radiation and relatively low manufacturing cost.
A liquid crystal display is a kind of passive light-emitting devices, and needs a backlight unit (BLU) to provide a light source to the liquid crystal display so as to make it display images. A backlight unit of a liquid crystal display known to the inventor, as illustrated in FIG. 1a, mainly includes a flexible printed circuit board 10 (short for FPCB), a light bar used as a light source and formed by a plurality of LEDs 11 (Light-Emitting Diodes), and a light guiding plate 12. A sectional view illustrated in FIG. 1b is obtained taken along a dotted line A-A′ in FIG. 1a, and the backlight unit further includes an adhesive tape 13 used for bonding the light guiding plate 12 and the flexible printed circuit board 10, and a diffusion plate 14 located on a side of the light guiding plate 12.
However, it can be seen from FIG. 1b that because the light guiding plate 12 and the flexible printed circuit board 10 are bonded by the adhesive tape 13, a gap exists between the flexible printed circuit board 10 and the light guiding plate 12, and in the meantime an expansion gap 15 needs to be set aside during the process of assembling the flexible printed circuit board 10 and the diffusion plate 14. Furthermore, because of the development trend of a narrow-bezel display, the distance between the light bar and a visible area of a liquid crystal module (short for LCM) is caused to be smaller and smaller. In this way, light emitted by the LEDs can pass through the gap and enter the visible area of the liquid crystal module, and thus a light leak phenomenon occurs. This light leak phenomenon restricts the quality of a liquid crystal panel greatly, and decreases the display effect of the liquid crystal display device.